The present invention finds significant use in the ammoxidation of both propylene and propane to produce acrylonitrile, and in general in the ammoxidation of olefins, paraffins and other starting materials to produce the corresponding nitrites. This reaction is well known and is described, for example, in U.S. Pat. No. 3,642,930 (olefins) or U.S. Pat. No. 4,897,504 (paraffins), the disclosures of which are incorporated herein by reference. In general, the ammoxidation reaction is accomplished by contacting the reactant olefin or paraffin (or other starting material), oxygen and ammonia, in the vapor phase, with a particular ammoxidation catalyst, at an elevated temperature and at atmospheric or near atmospheric pressure. The reaction may be carried out in the same manner and under the conditions generally set forth, for example, in the '930 patent or the '504 patent.
In addition to olefins and paraffins, oxygenated hydrocarbons can be ammoxidized with the known ammoxidation catalysts. For example, alcohols such as isopropanol, n-propanol, t-butyl alcohol, and aldehydes such as acrolein and methacrolein can be readily converted to nitriles. In general, the starting materials are olefins, paraffins, aldehydes and alcohols containing three or four carbon atoms. The general ammoxidation process for converting olefins, alcohols and aldehydes to the corresponding nitriles is well known and described for example in U.S. Pat. Nos. 3,642,930 and 4,897,504, and others assigned to The Standard Oil Company.
The following description of the ammoxidation reaction, both in the background and in the description of the invention, may use an olefin, sometimes specifically propylene, for exemplary purposes. The invention is not so limited and is applicable to ammoxidation reactions using any known starting material and particularly including paraffins in addition to olefins. It is further noted that, as would be understood by a person of skill in the art, it may be necessary to adjust the process, including changing catalysts used, according to the particular starting material employed and according to the products desired to be produced. For convenience herein, the term "hydrocarbon" may be employed for referring to the organic feed material, be it olefin, paraffin or other known ammoxidation feed material.
In monitoring and controlling the ammoxidation reaction, it has heretofore been the practice in the industry to operate the reactor based on test results obtained from previous operations of the reactor, where the test results are obtained from quality control procedures known as "recovery runs". Recovery runs are laboratory chemical analyses performed on collected samples of the effluent stream and/or collected products of the ammoxidation reaction (i.e., a day's production). Recovery runs require a minimum of several hours to perform, so cannot provide contemporaneous, real-time information as to the ammoxidation reaction. For these reasons, recovery runs can only provide hindsight information as to the parameters of operation of the ammoxidation reaction. The industry has long sought both more rapid analysis of the reaction products and a way to provide such information in real time, so as to allow the control and optimization of the ammoxidation reaction during the course of a reaction, i.e., in "real-time".